In many cases plastic materials can be effectively used in place of heavier and more expensive materials such as, for example, steel. However, where such materials are to be used in place of the heavier and more expensive materials, strength and finish may be of particular concern. One example of such a scenario is steel panels used in construction of, for example, automobiles where the surface may be painted and a high gloss without evident patterns is desired.
Carbon fiber reinforced plastic materials offer excellent strength to weight ratios and are well suited to replacing heavier and more expensive materials. However, such carbon fiber reinforced plastic materials have drawbacks when used in areas where an aesthetically pleasing finish is desired. For example, where exemplary steel materials may provide a roughness Ra of approximately 0.15 μm, an exemplary carbon fiber reinforced plastic material may provide a roughness Ra 75% higher, or up to 0.60 μm. This effect is further exacerbated when the material is subsequently finished, e.g., painted and optionally cured.
The surface quality of continuous carbon fiber reinforced plastic components is poor (e.g. high roughness) because the fiber creates some distortions in the surface smoothness. When these components are painted, the fiber patterns are clearly visible, this is known in the art as “fiber print through.”
This phenomenon is caused, at least in part, by the shrinkage of the thermoplastic resin surrounding the carbon fibers and/or the carbon fiber bundles during the cooling phase of the molding process. This is known in the art as molding shrinkage.
Additionally, in the case of painted panels, during painting and curing (e.g. at around 140° C.), the thermoplastic resin expands again, and this expansion is greater than the carbon fibers. When cooling, the resin again shrinks back around the carbon fibers and carbon fiber bundles.
The difference in thermal expansion coefficients between these materials is one of the causes of surface distortion during painting. Both phenomenon mentioned above result in higher roughness and lower finish quality than the commonly used steel materials.
Carbon fiber materials forming panels currently available on the market are thermoset cured materials and they require intensive post-processing to achieve the same wave scan values as steel. Such post-processing can be expensive, time consuming, and labor intensive, and may still not reach the surface quality of steel. Therefore, it would be beneficial to improve still the finish quality while also reducing the resources required to obtain a suitable finish on these materials.
DE 10 2012007839 discloses a multilayer fiber plastic-composite component using a thermoset resin. This composite component has at least one fiber plastic layer made of a matrix resin and a fiber material embedded with carbon fibers. The visible surface is provided with a transparent glass layer, which is connected with the fiber plastic layer by the matrix resin. This material, as noted above, requires extensive post processing to render it useful in applications where an aesthetically pleasing finish is desired.
Embodiments of the present disclosure are intended to overcome the shortcomings in the current state-of-the-art.